This study assesses correlates of the use and non-use of illicit drugs and medicinal substances among 6,405 secondary school students in an entire district. Responses to a questionnaire administered to the students were analyzed separately by sex and grade level (7-9 vs. 10-12). Some findings were: (1) about one-third of the high school students (10-12) were using illicit drugs, while one-tenth of junior high school students (7-9) were users; (2) over two-thirds of the grade 7-9 group and over half the grade 10-12 group reported no drug usage at all; and (3) legal substances were most frequently used by those reporting usage, with coffee, alcohol and tobacco most popular and illicit drugs (except marijuana) used by less than one-tenth of the sample. Friends were very important in shaping drug-use patterns, with users being eight times as likely to have a best firend also using drugs. Users describe themselves as social misfits and may turn to drugs as a means of finding friends. The data suggest that, at least for this district, the majority of adolescents are relatively uninvolved with illicit drugs. Educational programs must differentiate between the relatively small user group, those sporadically involved, and those who are non-users. (Author/CJ)